Solid-body catheter including lateral distal openings

ABSTRACT

A catheter for vascular insertion, including a catheter body defining a first lumen and a second lumen, and including a distal region. The distal region includes an atraumatic nose portion defining a first distal opening in fluid communication with the first lumen, and a second distal opening in fluid communication with the second lumen. The distal region also includes a first lateral opening defined by the catheter body and in fluid communication with the first lumen, and a second lateral opening defined by the catheter body and in fluid communication with the second lumen. One or both of the first and second lateral openings may be defined by an angle cross-cut through an outer perimeter of the catheter body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/032,858, filed Sep. 20, 2013, now U.S. Pat. No. 9,174,019, which is acontinuation of U.S. patent application Ser. No. 13/657,604, filed Oct.22, 2012, now U.S. Pat. No. 8,540,661, which is a continuation of U.S.patent application Ser. No. 12/414,467, filed Mar. 30, 2009, now U.S.Pat. No. 8,292,841, which is a continuation-in-part of U.S. patentapplication Ser. No. 12/253,870, filed Oct. 17, 2008, now U.S. Pat. No.8,066,660, which claims the benefit of the following applications: U.S.Provisional Application No. 60/983,032, filed Oct. 26, 2007; U.S.Provisional Application No. 61/036,848, filed Mar. 14, 2008; and U.S.Provisional Application No. 61/085,748, filed Aug. 1, 2008. Each of theafore-referenced applications is incorporated herein by reference in itsentirety.

BRIEF SUMMARY

Briefly summarized, embodiments of the present invention are directed toa split-tip catheter for placement within the vasculature of a patient.The catheter is configured for use in hemodialysis treatments, thoughthe principles of the present invention may be extended to othercatheters employed in other uses in addition to hemodialysis.

In one embodiment, the split-tip catheter includes a catheter body thatdefines a first lumen and a second lumen. The catheter body furthercomprises a split distal region, including a venous segment that definesa distal portion of the first lumen and an arterial segment that definesa distal portion of the second lumen. The venous segment includes arecess extending proximally of a nose portion, and a lateral opening influid communication with the first lumen.

The arterial segment is separate from the venous segment in the splitdistal region and is removably seatable in the recess provided by thevenous segment such that it “nests” therein. This nesting of thearterial segment with the venous segment provides a columnar profile forthe split distal region during its advancement into and through thepatient's vasculature, enabling the distal region to advance as amonolithic structure and thus easing its advancement through tortuouspaths and past pathway obstacles. The segments are maintained in theirnested state via a guidewire that is passed through both segments and isremovable after the catheter has been suitably placed. Similar to thevenous segment, the arterial segment also includes a lateral opening influid communication with the second lumen.

An example of a split-tip catheter that can include aspects ofembodiments of the present invention is disclosed in U.S. Pat. No.6,001,079, entitled “Multilumen Catheter, Particularly forHemodialysis,” which is incorporated herein by reference in itsentirety.

In one embodiment, the distal region of the catheter is un-split, butincludes symmetrically opposed lateral openings, as well as distalopenings, in communication with the first and second lumens. The lateraland distal openings of the first and second lumens in the distal regionprovide a functional stagger for blood flow in both forward and reversecatheter flow directions. As will be further described, theconfiguration of the above openings is intended to reduce the likelihoodof uptake and recirculation by one lumen of the catheter of treatedblood just returned to the vessel via the other lumen, thus increasingcatheter efficiency.

These and other features of the present invention will become more fullyapparent from the following description and appended claims, or may belearned by the practice of the invention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thepresent invention, a more particular description of the invention willbe rendered by reference to specific embodiments thereof that areillustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. The invention willbe described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 is a perspective view of a catheter assembly including asplit-tip distal region configured in accordance with one exampleembodiment of the present invention;

FIG. 2 is a perspective view of a catheter assembly including a splittip distal region and a pre-curved catheter body, according to oneembodiment;

FIGS. 3A-3D are two perspective views, a side view, and a top view,respectively, of the distal region of the split-tip catheter of FIG. 1;

FIGS. 4A and 4B are a perspective and a side view, respectively, of thedistal region of the split-tip catheter of FIG. 1, wherein a guidewireis inserted therethrough to maintain a venous segment and arterialsegment in a nested configuration;

FIGS. 5A and 5B are side views of the distal region of the split-tipcatheter of FIG. 1 showing the flow of blood therethrough in a “forward”direction (FIG. 5A) and a “reverse” direction (FIG. 5B) when thecatheter is disposed in a vasculature of a patient;

FIG. 5C is a side view of the distal region of the split-tip catheter ofFIG. 1;

FIG. 5D is a cross sectional view of the catheter of FIG. 5C taken alongthe line 5D-5D;

FIG. 5E is a cross sectional view of the catheter of FIG. 5C taken alongthe line 5E-5E;

FIG. 5F is a cross sectional view of the catheter of FIG. 5C taken alongthe line 5F-5F;

FIG. 5G is a cross sectional view of the catheter of FIG. 5C taken alongthe line 5G-5G;

FIG. 5H is a distal end view of the catheter of FIG. 5C taken along theline 5H-5H;

FIGS. 6A and 6B are a perspective and a side view, respectively, of adistal region of a split-tip catheter configured in accordance with oneembodiment;

FIG. 7 is a simplified view of the split-tip catheter of FIG. 1 afterinsertion into a vasculature of a patient;

FIG. 8A is a perspective view of a subcutaneous tunneler configured inaccordance with one example embodiment of the present invention;

FIG. 8B is a side view of the tunneler shown in FIG. 8A;

FIGS. 8C and 8D are side and top views, respectively, of the tunnelershown in FIG. 8A;

FIGS. 9A-9D show various steps of the insertion of the subcutaneoustunneler of FIG. 8A in a distal end of a split-tip catheter, such asthat shown in FIG. 1;

FIGS. 10-12 are side views of barb configurations for the tunneler ofFIG. 8A, according to embodiments of the present invention;

FIGS. 13A-13C are perspective, bottom, and top views, respectively, of asplit-tip catheter including a distal region configured in accordancewith one embodiment of the present invention;

FIGS. 14A-14C are perspective, bottom, and top views, respectively, of asplit-tip catheter including a distal region configured in accordancewith one embodiment;

FIGS. 15A-15C are perspective, bottom, and top views, respectively, of asplit-tip catheter including a distal region configured in accordancewith one embodiment;

FIGS. 16A-16C are perspective, bottom, and top views, respectively, of asplit-tip catheter including a distal region configured in accordancewith one embodiment;

FIGS. 17A-17C are perspective, bottom, and top views, respectively, of asplit-tip catheter including a distal region configured in accordancewith one embodiment;

FIGS. 18A-18D are perspective, bottom, top, and cross sectional views,respectively, of a split-tip catheter including a distal regionconfigured in accordance with one embodiment;

FIGS. 19A-19D are perspective, bottom, top, and cross sectional views,respectively, of a split-tip catheter including a distal regionconfigured in accordance with one embodiment;

FIGS. 20A-20C are perspective, bottom, and top views, respectively, of asplit-tip catheter including a distal region configured in accordancewith one embodiment;

FIGS. 21A-21C are perspective, bottom, and top views, respectively, of asplit-tip catheter including a distal region configured in accordancewith one embodiment of the present invention;

FIGS. 22A-22B are perspective views of a split-tip catheter including adistal region configured in accordance with one embodiment of thepresent invention;

FIGS. 23A-23C are perspective views of a split-tip catheter including adistal region configured in accordance with one embodiment of thepresent invention;

FIGS. 24A-24F are various views of the distal region of a catheter inaccordance with one example embodiment;

FIGS. 25A-25C are various cross sectional views of the distal region ofthe catheter of FIG. 24A;

FIG. 26A is a distal end view of the catheter of FIG. 24C taken alongthe line 26A-26A;

FIG. 26B is a cross sectional view of the catheter of FIG. 24C takenalong the line 26B-26B;

FIG. 27 is a simplified view of the catheter of FIG. 24A after insertioninto a vasculature of a patient;

FIGS. 28A-28D are various views of a distal region of a catheter body,according to one example embodiment;

FIGS. 29A-29B are various views of a distal region of a catheter body,according to another example embodiment; and

FIG. 30 is a side view of a distal region of a catheter body includingstaggered lateral openings in accordance with one example embodiment.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

Reference will now be made to figures wherein like structures will beprovided with like reference designations. It is understood that thedrawings are diagrammatic and schematic representations of exemplaryembodiments of the invention, and are not limiting of the presentinvention nor are they necessarily drawn to scale.

FIGS. 1-30 depict various features of embodiments of the presentinvention, which are generally directed to a split-tip catheter forplacement within the vasculature of a patient. The catheter isconfigured for use in renal replacement therapies such as hemodialysisor blood purification, though the principles of the present inventionmay be extended to other catheters employed in other uses in addition tothese. Such catheters are typically employed in long-term or chronicplacement scenarios such as a placement of 30 days or more, though theprinciples to be described herein can also apply to short and mid-termcatheter placements as well.

In accordance with one example embodiment, the split-tip portion of thecatheter includes separate venous and arterial segments that areemployed for simultaneously infusing and aspirating blood from a vein orother vessel of a patient's vasculature during hemodialysis treatments.The distal ends of the venous and arterial segments can be staggered toreduce the likelihood of recirculation by the arterial segment oftreated blood just returned to the vessel by the venous segment, thusincreasing catheter efficiency. In addition, both the venous andarterial segments are configured with openings, including laterallydisposed openings, to further increase catheter efficiency duringhemodialysis.

Embodiments of the split-tip catheter to be described herein furtherinclude a nested split-tip configuration, wherein the arterial segmentof the catheter seats in a correspondingly shaped recess provided by aportion of the venous segment. When seated in this manner, the arterialsegment defines with the venous segment a smooth, cylindrical outersurface, thus enabling the catheter to be introduced into and advancedin the patient's vasculature while avoiding snagging or obstructionsthat would otherwise cause the catheter to catch or bind therewith. Thenested split-tip design further provides a guidewire channel forenabling a guidewire to be passed through both the venous and arterialsegments to maintain the two segments in the nested configuration duringcatheter insertion into the vasculature. Once the catheter is properlypositioned, the guidewire may be removed and the venous and arterialsegments are free to separate from one another within the vessel, thusproviding desired separation therebetween. A subcutaneous tunneler isalso provided herein for assistance in subcutaneously tunneling thecatheter.

In one embodiment, the distal region is un-split, but includessymmetrically opposed lateral openings, as well as distal openings, incommunication with the first and second lumens for providing afunctional stagger for blood flow in both forward and reverse catheterflow directions. The lateral and distal openings of the first and secondlumens in the distal region provide a functional stagger for blood flowin both forward and reverse catheter flow directions. As with the otherembodiments described herein, the configuration of the above openings isintended to reduce the likelihood of fluid recirculation so as toincrease catheter efficiency.

For clarity it is to be understood that the word “proximal” refers to adirection relatively closer to a clinician using the device to bedescribed herein, while the word “distal” refers to a directionrelatively further from the clinician. For example, the end of acatheter placed within the body of a patient is considered a distal endof the catheter, while the catheter end remaining outside the body is aproximal end of the catheter. Further, the words “including,” “has,” and“having,” as used herein, including the claims, shall have the samemeaning as the word “comprising.”

Reference is first made to FIG. 1, which depicts various features of ahemodialysis split-tip catheter assembly, generally designated at 10,according to one example embodiment of the present invention. As shown,the catheter 10 includes an elongate catheter body 11 including aproximal end 11A and a distal end 11B. The elongate catheter body 11defines a first lumen 12 and a second lumen 14 (FIG. 3B) thatlongitudinally extend from the proximal end 11A to the distal end 11Bthereof. The lumens 12 and 14 can have one or more cross sectionalshapes along their respective lengths, including round, oval, andD-cross sectional shapes. The catheter body 11 can define more than twolumens, if desired. As shown in FIG. 5B, the first and second lumens 12,14 are split along a common septum of the catheter body 11. The catheterbody 11 can be formed of a variety of suitable materials, includingpolyurethane, silicone, etc.

A bifurcating hub 15 is included at the catheter body proximal end 11A,providing fluid communication between the first and second lumens 12, 14and arterial extension leg 16 and venous extension leg 18, respectively.The extension legs 16, 18 each include a luer connector 16A, 18A and aclamp 16B, 18B. So configured, the extension legs 16, 18 provide fluidcommunication with the first and second lumens 12 and 14 so as to enablethe infusion or aspiration of fluids from a vein or other vessel orportion of a patient's vasculature. As such, fluid infusion oraspiration devices, such as a hemodialysis apparatus for example, may beconnected to the catheter assembly 10 via the luer connectors 16A, 18A,thus providing intravascular access to the patient. The catheter body 11further includes a cuff 19 for providing anchoring of the catheter bodyinto body tissue when the catheter assembly is subcutaneously tunneled.

Reference is made to FIG. 2, which shows the catheter assembly 10,according to another example embodiment, wherein the catheter body 11includes a pre-curved portion 18C intermediate the proximal and distalends 11A, 11B thereof. That is, in an unstressed configuration thecatheter assumes the shape shown in FIG. 2. The pre-curved portion 18Cenables the exterior proximal portion of the catheter assembly 10 toextend downward against the patient's body once the distal portion ofthe catheter assembly has been placed in the vasculature.

Both FIGS. 1 and 2 further include a distal tip region, generallydesignated at 20, that is configured in accordance one exampleembodiment of the present invention, the details of which are givenbelow. It should be appreciated that the distal tip region to bedescribed below can be included with hemodialysis catheters, such asthose shown in FIGS. 1 and 2, or with other catheters, such as centralvenous catheters, for example.

Reference is now made to FIGS. 3A-3D, which depict various detailsregarding the distal tip region 20 of FIG. 1 as briefly discussed above.The distal tip region 20 generally includes the split-tip distal portionof the catheter assembly 10, including a distal venous segment 22 thatdefines a distal portion of the first lumen 12, and a distal arterialsegment 24 that defines a distal portion of the second lumen 14. Asshown in FIG. 3B, the venous and arterial segments 22, 24 are splitalong a common septum of the catheter body 11 that separates the firstlumen 12 from the second lumen 14.

The venous segment 22 includes a nose portion 30 at the distal endthereof. In the present embodiment, the nose portion 30 generallydefines a tapered, conical shape, though this shape may be varied, aswill be seen further below. The tapered shape of the nose portion 30reduces insertion forces during placement and minimizes abrasion betweenthe nose portion surface and the walls of the vessel in which the distalregion of the catheter is disposed. A venous distal opening 32A isdefined on the tapered portion of the nose portion 30 and is in fluidcommunication with the distal portion of the first lumen 12 defined bythe venous segment. A guidewire channel 32B proximally extends from ahole defined at the distal end of the nose portion 30 and is incommunication with the second lumen 14 of the arterial segment 24, inthe manner described below, to enable selective nesting of the arterialsegment with the venous segment 22 during catheter insertion. Of course,these openings, as well as the other catheter openings to be describedbelow, can vary in size and placement from what is explicitly describedherein.

The venous segment 22 further defines a recess 36 proximal to the noseportion 30 that is sized to correspond to the shape of an outer surfaceof the arterial segment 24. The arterial segment 24 can thus beselectively and removably seated, or “nested” in the recess 36, thusproviding a smooth, cylindrical outer surface profile for the distal tipregion 20 of the catheter body 11 during advancement of the catheterassembly 10 through a subcutaneous tunnel or vasculature path.

In greater detail, and as best seen in FIG. 3C, the recess 36 defines aconcavely shaped distal surface 36A that corresponds to the convex shapeof a distal surface 24A of the arterial segment 24. Note that an upperportion of the curved distal surface 24A is rounded so as to reducesnagging of the arterial segment 24 during vasculature navigation.

A distal end of the arterial segment 24 includes an arterial distal endopening 34, which is defined on the curved distal surface 24A thereof.The arterial distal end opening 34 is in fluid communication with thedistal portion of the arterial lumen 14 defined by the arterial segment24. In addition, the arterial distal end opening 34 coaxially alignswith the guidewire channel 32B of the venous nose portion 30 when thearterial segment 24 is nested and seated in the recess 36 of the venoussegment 22. So positioned, a guidewire 46 can be passed through theguidewire channel 32B of the venous nose portion 30, the arterial distalend opening 34, and the second lumen 14, as shown in FIGS. 4A and 4B, tomaintain the arterial segment 24 in a nested configuration in the recess36 of the venous segment 22. This nested configuration can be achievedin other ways as well, including in one embodiment a bio-dissolvableadhesive that temporarily binds the two segments together until catheterplacement within the vasculature is complete, after which the adhesivedissolves to enable the segments to separate.

With the arterial segment 24 nested in the recess 36 behind the venousnose portion 30, the distal tip region 20 of the catheter assembly 10presents as a low drag, columnar structure with a tapered noseconfiguration. This configuration aids in guiding the distal tip region20 through the soft tissues and vasculature of the patient duringplacement or catheter exchange procedures using over-the-wire techniquesfor instance. Later, when the catheter assembly 10 is properlypositioned, the venous segment 22 and the arterial segment 24 canseparate from one another within the vessel, as shown in FIG. 3C forexample, as a result of removal of a guidewire used to position thecatheter. This separation of the venous and arterial segments 22 and 24assists in reducing recirculation of treated blood during hemodialysisprocedures. Note here that, in another embodiment, the nestingconfiguration of the distal tip region could be interchanged such thatthe recess is defined by the arterial lumen and the venous lumen neststherein.

FIGS. 3A-3D further depict the venous segment 22 as including along itslength a venous lateral opening 42 defined proximate the nose portion30. Similarly, the arterial segment 24 includes an arterial lateralopening 44 defined proximate the distal end of the arterial segment 24.The lateral openings 42 and 44 can take various shapes andconfigurations as will be shown further below, but in the presentembodiment the lateral openings are defined by compound-anglecross-drilled cuts through the outer surface of the respective segment22 or 24 to establish communication with the respective first or secondlumens 12, 14. In one embodiment, such cuts are referred to as “skive”cuts.

In one embodiment, the longitudinal axis of each cross cut of thelateral openings 42, 44 defines an angle of about 35 degrees with alongitudinal axis of the respective venous or arterial segment 22, 24,though this angle can vary in one embodiment from about 20 to about 90degrees. The longitudinal axis of each cross cut of the lateral openings42, 44 further defines an angle in one embodiment of about 15 degreeswith a plane bisecting the first lumen 12 and second lumen 14, i.e.,coplanar with the septum separating the first and second lumens proximalof the distal tip region 20, though this angle can vary in oneembodiment from about 0 to about 45 degrees. This angular characterimparts a lateral directional component to fluid flow out of eitherlateral opening 42, 44, as represented by the flow arrows in FIG. 3D.

In addition, the longitudinal axes of the lateral openings 42, 44 aresymmetrically opposed in direction from one another, as best shown inFIG. 3D, so as to ensure fluid entry and exit from the lateral openingsoccurs on opposite sides of catheter assembly 10, thus reducingrecirculation of already treated blood. Furthermore, this symmetryensures similar fluid flow characteristics to be realized even whenfluid flow through the catheter assembly 10 is reversed. Moreover, thelateral openings 42, 44 extend circumferentially about a portion of thecircumference of the respective venous or arterial segment 22 or 24,thus helping to prevent aspiration-related suck-up of the segmentagainst the vessel wall. It is noted that in one embodiment the size ofthe lateral openings 42, 44 is such that each can accommodate theentirety of fluid flow through their respective first or second lumens12, 14. Thus, the inclusion of the lateral openings 42, 44 with theircorresponding distal openings 32A, 34 provides a redundant system suchthat any clotting that occurs at one opening will not significantlyimpact fluid throughput of the respective venous or arterial segment.

It should be appreciated that the labels “venous” and “arterial” as usedabove in describing the various components of the present split-tipcatheter are employed for sake of convenience in describing aspects ofembodiments of the present invention. Indeed, though the arterialsegment is normally employed in hemodialysis procedures for aspiratingblood from the blood vessel in which the catheter is disposed and thevenous segment for returning already treated blood to the vessel, thiscan be reversed such that blood is returned via the arterial segment andaspirated by the venous segment. As such, the present invention shouldnot be considered limited by the use of this and other descriptiveterminology herein.

As can be seen in FIGS. 3D and 4B, the nose portion 30 of the venoussegment 22 is configured such that it provides a “shadow” for thearterial segment 24 when the arterial segment is brought into contactwith the venous segment, such as when it seats in the recess 36 of thevenous segment. In other words, the outer diameter of the nose portion30 is similar to that of the catheter body 11 proximal of the distal tipregion 20 such that the arterial segment 24 is “shielded” by the noseportion when nested with the recess 36. This provides for relative easeof catheter insertion, such as when the distal tip region 20 is passedthrough a valved introducer during initial catheter placement, orthrough a subcutaneous tunnel in an over-the-guidewire catheter exchangeprocedure.

In one embodiment, the nose portion 30 is defined via a radiofrequency(“RF) tipping process, wherein a dual lumen catheter is split to definetwo lumen segments, i.e., the venous and arterial segments, in a distaltip region thereof. The distal portions of the lumen segments are bondedtogether via RF tipping to define the shape of the nose portion as shownin FIGS. 3A-3D. The distal tip region is then sliced to define therecess 36 and separate the arterial segment from the venous segment.Note that other forming processes may also be employed to define thedistal tip region in accordance with other embodiments and asappreciated by one skilled in the art.

Reference is now made to FIGS. 5A and 5B in describing flowcharacteristics with respect to the split-tip configuration of thedistal tip region 20 of the present catheter assembly 10. FIGS. 5A and5B shows the distal tip region 20 with the arterial segment 24 in itsunseated state with respect to the venous segment 22 after the catheterassembly 10 has properly positioned within a vessel of a patient. Arrow48 shows the direction of bloodflow past the distal tip region 20 withinthe patient's vessel.

In greater detail, FIG. 5A shows fluid flow through the distal tipregion 20 in a “forward” direction, wherein blood is aspirated by thesecond lumen 14, or “uptake” lumen, for removal from the body andtreatment by a hemodialysis apparatus or for some other suitablepurpose. Aspirated blood enters the second lumen 14 via both thearterial distal end opening 34 and the arterial lateral opening 44 ofthe arterial segment 24. However, because the second lumen 14 is undernegative pressure during aspiration, the majority of blood aspirated bythe second lumen is removed via the arterial lateral opening 44 due toits relatively more proximal position with respect to the pressuredifferential in the proximate vessel region.

Similarly, blood is infused, or returned, to the vessel by the firstlumen 12, or “return” lumen, after treatment by a hemodialysis apparatusor some other suitable purpose. Infused blood exits the first lumen 12from both the venous distal opening 32A and the venous lateral opening42 of the venous segment 22. However, because the second lumen 12 isunder positive pressure during infusion, the majority of blood returnedto the bloodstream by the first lumen exits via the venous distalopening 32A due to its relatively more distal position with respect tothe pressure differential in the proximate vessel region. Note that thisarrangement produces an effective stagger distance F in the “forward”direction between the primary aspiration site, i.e., the arteriallateral opening 44, and the primary infusion site, i.e., the venousdistal opening 32A. This effective stagger distance, together with thelateral orientation of the lateral openings 42, 44 provides for lowrecirculation of already-treated blood within the vessel, recirculationbeing defined as already-treated blood that is returned to thebloodstream via the venous lumen being immediately aspirated by thearterial lumen to be re-treated. Such recirculation is undesirable as itresults in lower treatment efficiency and longer treatment time.

During hemodialysis procedures, it is sometimes necessary to reverse theblood flow through the catheter assembly 10. FIG. 5B shows fluid flowthrough the distal tip region 20 during such a “reverse” flow situation.In contrast to the forward flow conditions of FIG. 5A, the second lumen14 in FIG. 5B is employed to infuse blood into the vessel via thearterial lumen 24, while the first lumen 12 aspirates blood from thevessel via the venous lumen 22. In this configuration, the majority ofinfused blood enters the vessel via the arterial distal opening 34 ofthe arterial segment 24, while the majority of aspirated blood isremoved via the venous lateral opening 42 of the venous segment 22. Thisarrangement produces an effective stagger distance R in the “reverse”direction between the primary aspiration site, i.e., the venous lateralopening 42, and the primary infusion site, i.e., the arterial distalopening 34. Thus, it is seen that a desired stagger between the primaryinfusion and aspiration points is achieved regardless of the directionin which the catheter is operating.

Reference is now made to FIGS. 5C-5H. In one embodiment, the proximalportions of the first and second lumens 12, 14 of the catheter body 11define a “D”-shaped cross sectional shape, as seen in FIGS. 5D and 5E.The first and second lumens 12, 14 each include a loft, or transitionregion 45, wherein the cross sectional shape of each lumen changes froma “D” shape to an oval shape, which oval shape continues toward thedistal end of the distal tip region 20, as seen in FIGS. 5F and 5G.Definition of the transition region 45 and the oval shape of the distalportions of the first and second lumens 12, 14 can be accomplished byone of several suitable methods, including heat forming, molding,extrusion, etc.

Note that the oval shape of the first and second lumens 12, 14 isprovided in the region proximate the lateral openings 42, 44. Thisprovides additional stiffness and strength to the catheter body 11 inthis region while also maintaining an acceptable inter-luminal thicknessfor the central septa of the venous and arterial segments 22, 24. Inother embodiments, other cross sectional shapes can be defined by thecatheter body. Or, in another embodiment the “D”-shaped cross sectionallumens continue distally to the distal end of the catheter body. In yetanother embodiment, the first and second lumens define oval crosssectional shapes along most or all of the catheter body length. FIG. 5Hshows an end view of the catheter body depicted in FIG. 5C.

Note that the configuration of the distal tip region 20 can varyaccording to need or design. FIGS. 6A and 6B show one such variation,wherein a nose portion 31 of the venous segment 22 includes the venousdistal opening 32A at the distal end of the nose portion and not alongthe tapered surface, as in the configuration in FIG. 1. Further, aguidewire channel 33 extends from just inside the venous distal opening32A and through the nose portion 31 so as to establish communicationwith the arterial distal opening 34 of the arterial segment 24 when thearterial and venous segment 22 are nested. Thus, these and othervariations in the distal tip region are contemplated as falling withinthe principles of the present invention.

Reference is now made to FIGS. 8A-8D in describing various aspects of asubcutaneous tunneling device (“tunneler”), generally designated at 60,for use in subcutaneously tunneling a portion of the catheter assembly10 in the body of the patient. FIG. 7 depicts such a tunneled state ofthe catheter assembly 10, wherein a tunneled region 52 intermediate theproximal and distal ends of the catheter body 11 is disposed underneaththe skin of the patient 50. As shown, the proximal portion of thecatheter assembly 10, including the hub 15 and extension legs 16 and 18,is exposed proximal the tunneled region 52. Correspondingly, a distalportion of the catheter assembly 10 is shown distal of the tunneledregion 52 and inserted through an incision site 54 into the patient'svasculature such that the distal tip region 20 is positioned in adesired location, such as in a lower region of the superior vena cave(“SVC”). The cuff 19 (FIG. 1) is included in the tunneled region 52 ofthe catheter assembly 10 such that tissue ingrowth into the cuff may beachieved to subcutaneously anchor the catheter to the patient's body andprevent unintended movement of the catheter. The process by which thetunneling configuration shown in FIG. 7 is achieved is referred to asantegrade tunneling.

As shown in FIGS. 8A-8D, the tunneler 60 generally includes shaft 62, asleeve 64 slidably mounted on the shaft, and a catheter connector 66.Composed of materials including malleable stainless steel or othersuitable material, the shaft 62 is used during the tunneling procedureto define the tunnel through which the catheter will be pulled. Theshaft 62 tapers down to a first end 62A and includes a second end 62B atwhich end the catheter connector 64 is attached. The shaft includes abend 62C, which acts as a slide stop for the sleeve 64.

The sleeve 64 is composed of materials including flexible plastic e.g.,polyethylene for instance, and includes a hollow inner bore 74 (FIG. 9D)that slidably receives the shaft 62 therethrough. The inner bore 74 ofthe sleeve 64 extends between a tapered down first end 64A and a secondend 64B that is sized to selectively slide over the catheter connector66. Thus, the sleeve 64 is selectively slidable from a retractedposition, in which the tapered first end 64A stops against the shaftbend 62C, and an extended position, in which the sleeve covers theentirety of the catheter connector 66.

Composed of materials including biocompatible plastic for instance, thecatheter connector 66 includes a body defining a gripping portion 68 forenabling a clinician to grasp the tunneler 60, and a stepped end 68A atthe point of attachment of the catheter connector with the second end62B of the shaft 62. A nose stop 70 is included on the catheterconnector 66 and is shaped as to correspond with the distal portion ofthe catheter to which the catheter connector will attach. As will beseen, this enables a clinician to know when the catheter connector hasfully engaged the catheter prior to tunneling.

A barbed extension 72 including one or more barbs 72A extends from thecatheter connector nose stop 70 and is configured to extend into a lumenof the catheter to which the tunneler 60 will connect so as to provide aretention force therebetween. Note that the barbed extension 72 isoffset from a central longitudinal axis of the catheter connector 66,though this configuration may be modified according to the design of thecatheter to which the catheter connector is to connect.

Reference is now made to FIGS. 9A-9D in describing the manner ofattachment between the tunneler 60 and a distal end of a catheter, suchas the catheter assembly 10 shown in FIG. 1. Particularly, FIG. 9A showsthe alignment between a distal end of the catheter assembly 10 and thetunneler 60, wherein the barbed extension 72 is axially aligned with thevenous distal opening 32A of the venous segment 22 prior to insertion ofthe barbed extension into the catheter.

FIG. 9B shows the barbed extension 72 fully inserted into the venousdistal opening 32A, thus connecting the tunneler 60 with the catheterassembly 10. In this position, the nose portion 30 of the venous segment22 engages the nose stop 70 of the catheter connector 66, thus enablingthe clinician to determine when the connector is fully engaged with thecatheter assembly 10. Note that the barb 72A of the barbed extension 72engages the first lumen 12 via the venous distal opening 32A such thatthe outer surface of the segment is extended outward in the immediatevicinity of the barb.

As shown in FIG. 9C, once the catheter connector 66 of the tunneler 60is fully connected to the distal end of the catheter assembly 10, thesleeve 64 is slid forward to cover the entirety of the catheterconnector and its engagement with the catheter. As shown in FIG. 9D, thesleeve is slid forward until a shoulder 76 defined in the inner bore 74abuts the stepped end 68A of the catheter connector. Note that thesleeve inner bore 74 is sized so as to compress the distal portion ofthe catheter proximate its engagement with the catheter connector 66,thus increasing engagement of the barb 72A with the first lumen 12.

So attached, the tunneler 60 can then be used to define a subcutaneoustunnel in the patient and pull the catheter assembly 10 through thetunnel until properly positioned therein, as shown in FIG. 7. Once thecatheter assembly 10 is properly positioned, the sleeve 64 can be slidback to expose the catheter connector 66. The catheter connector 66 canthen be pulled so as to remove the barbed extension 72 from the firstlumen 12 of the venous segment 22, thus disconnecting the tunneler 60from the catheter assembly 10.

Note that the catheter connector 66 and its barbed extension 72 areconfigured to provide a retention force sufficient to enable thecatheter assembly 10 to be pulled by the tunneler through thesubcutaneous tunnel, but low enough to prevent damaging tensile loadsfrom being imposed on the distal end of the catheter. As such, thecatheter connector 66 is configured such that it can pulled out from theengagement with the catheter assembly 10 at a predetermined tensile loadthat is below the maximum tensile strength of the catheter distal end.Note also that engagement of the tunneler 60 with the catheter assembly10 as depicted herein is merely exemplary, and it is appreciated thatthe present tunneler can be employed with catheters having a variety ofconfigurations.

It should be further appreciated that the tunneler configuration can bevaried according to need or design. FIGS. 10-12 give examples ofalternative barbed extensions 78, 80, and 82, each having a differentconfiguration of barb(s) 78A, 80A, and 82A, respectively. These andother modifications to the tunneler 60 are therefore contemplated asfalling within the principles of the present invention. In addition, itis noted that the catheter assembly may be employed in both tunneled anduntunneled implementations, if desired.

Reference is now generally made to FIGS. 13A-21C in depicting varyingconfigurations of a split-tip catheter assembly in accordance withadditional example embodiments of the present invention. As theembodiments to be described below include elements similar to thosedescribed in connection with the catheter assemblies described above inconnection with FIGS. 1-5B, only selected elements of the followingembodiments will be discussed below.

FIGS. 13A-13C depict a distal tip region 120 of a split-tip catheterassembly including a venous segment 122 and an arterial segment 124 thatselectively seats, or nests, in a recess defined by the venous segment.A nose portion 130 of the venous segment 122 includes a venous distalopening 132A in fluid communication with a first lumen of the catheterbody 11 and a guidewire channel 132B. The arterial segment 124 includesan arterial distal opening 134 in fluid communication with a secondlumen of the catheter body 11. The arterial segment 124 is further incommunication with the guidewire channel 132B when the arterial segmentis nested with the venous segment 122.

The venous segment 122 includes a venous lateral opening 142 proximatethe nose portion 130, while the arterial segment 124 includes anarterial lateral opening 144 proximate the distal end thereof. Thelateral openings 142 and 144 are cross-cut, or skived in a mannersimilar to the embodiment shown in FIG. 1 and are in fluid communicationwith the first and second lumens, respectively, of the catheter body 11.Note that the nose portion 130 of the present embodiment has a roundedshape, in contrast to the tapered nose portion 30 of FIG. 1, though itis appreciated that various nose portion shape configurations arepossible.

FIGS. 14A-14C depict a distal tip region 220 of a split-tip catheterassembly including a venous segment 222 and an arterial segment 224 thatselectively seats, or nests, in a recess defined by the venous segment.A nose portion 230 of the venous segment 222 includes a nose portionopening 232 that serves as a guidewire channel by virtue of itsalignment with an arterial distal opening 234 of the arterial segment224 when the latter is nested with the venous segment 222. The arterialdistal opening 234 is further in fluid communication with a second lumenof the catheter body 11. As such, a guidewire passing through the secondlumen, the arterial distal opening 234 and the guidewire channel of thenose portion opening 232 enables the venous and arterial segments 222,224 to be maintained in a nested configuration during catheterinsertion.

The venous segment 222 includes a venous lateral opening 242 proximatethe nose portion 230, while the arterial segment 224 includes anarterial opening 248 proximate the distal end thereof. The lateralopening 242 is cross-cut, or skived in a manner similar to theembodiment shown in FIG. 1, while the arterial opening 248 defines atriangular opening. The openings 242, 248 are in fluid communicationwith the first and second lumens, respectively, of the catheter body 11.The nose portion 230 of the present embodiment has a rounded shape, incontrast to the tapered nose portion 30 of FIG. 1, though it isappreciated that various nose portion shape configurations are possible.Also, it is appreciated that the openings can each define one of avariety of configurations.

FIGS. 15A-15C depict a distal tip region 320 of a split-tip catheterassembly including a venous segment 322 and an arterial segment 324 thattogether define a nose portion 330. The venous segment 322 includes avenous distal opening 332A in fluid communication with a first lumen ofthe catheter body 11. The arterial segment 324 includes an arterialdistal opening 334 in fluid communication with a second lumen of thecatheter body 11.

The venous segment 322 includes a venous lateral opening 342 proximatethe nose portion 330, while the arterial segment 324 includes anarterial lateral opening 344 proximate the distal end thereof. Thelateral openings 342, 344 are cross-cut, or skived in a manner similarto the embodiment shown in FIG. 1. The lateral openings 342, 344 are influid communication with the first and second lumens, respectively, ofthe catheter body 11. The distal ends of the venous segment 322 andarterial segment 324 are un-staggered with respect to one another so asto enable both lateral openings to be placed in a single desiredlocation within the patient's vasculature, such as in the SVC forinstance.

The nose portion 330 of the present embodiment has a rounded shape, incontrast to the tapered nose portion 30 of FIG. 1, though it isappreciated that various nose portion shape configurations are possible.Also, it is appreciated that the lateral openings can each define one ofa variety of configurations.

FIGS. 16A-16C depict a distal tip region 420 of a split-tip catheterassembly including a venous segment 422 and an arterial segment 424 thatselectively seats, or nests, in a recess defined by the venous segment.A nose portion 430 of the venous segment 422 includes a nose portionopening 432 that serves as a guidewire channel by virtue of itsalignment with an arterial distal opening 434 of the arterial segment424 when the latter is nested with the venous segment 422. The arterialdistal opening 434 is further in fluid communication with a second lumenof the catheter body 11. As such, a guidewire passing through the secondlumen, the arterial distal opening 434 and the guidewire channel of thenose portion opening 432 enables the venous and arterial segments 422,424 to be maintained in a nested configuration during catheterinsertion.

The venous segment 422 includes a venous lateral opening 442 proximatethe nose portion 430, while the arterial segment 424 includes anarterial lateral opening 444 proximate the distal end thereof. Thelateral openings 442, 444 are cross-cut, or skived in a manner similarto the embodiment shown in FIG. 1. The lateral openings 442, 444 are influid communication with the first and second lumens, respectively, ofthe catheter body 11. The nose portion 430 of the present embodiment hasa rounded shape, in contrast to the tapered nose portion 30 of FIG. 1,though it is appreciated that various nose portion shape configurationsare possible. Also, it is appreciated that the lateral openings can eachdefine one of a variety of configurations.

FIGS. 17A-17C depict a distal tip region 520 of a split-tip catheterassembly including a venous segment 522 and an arterial segment 524 thatselectively seats, or nests, in a recess defined by the venous segment.A nose portion 530 of the venous segment 522 includes a nose portionopening 532 that serves as a guidewire channel by virtue of itsalignment with an arterial distal opening 534 of the arterial segment524 when the latter is nested with the venous segment 522. The arterialdistal opening 534 is further in fluid communication with a second lumenof the catheter body 11. As such, a guidewire passing through the secondlumen, the arterial distal opening 534 and the guidewire channel of thenose portion opening 532 enables the venous and arterial segments 522,524 to be maintained in a nested configuration during catheterinsertion.

The venous segment 522 includes a venous lateral opening 542 proximatethe nose portion 430, while the arterial segment 524 includes anarterial lateral opening 544 proximate the distal end thereof. Thelateral openings 542, 544 are semi-circular in shape, as best seen inFIGS. 17B and 17C. The lateral openings 542, 544 are in fluidcommunication with the first and second lumens, respectively, of thecatheter body 11 and are sized and configured so as to assist in fanningout fluid exiting therefrom. The nose portion 530 of the presentembodiment has a rounded shape, in contrast to the tapered nose portion30 of FIG. 1, though it is appreciated that various nose portion shapeconfigurations are possible. Also, it is appreciated that the lateralopenings can each define one of a variety of configurations.

FIGS. 18A-18D depict a distal tip region 620 of a split-tip catheterassembly including a venous segment 622 and an arterial segment 624 thattogether define a nose portion 630. The venous segment 622 includes avenous distal opening 632A in fluid communication with a first lumen ofthe catheter body 11. The arterial segment 624 includes a distal openingas part of a guidewire channel 632B. As best seen in FIG. 18D, theguidewire channel 632B is in fluid communication with a second lumen ofthe catheter body 11, but is angled so as to also communicate with thefirst lumen defined by the venous segment 622. Thus, the guidewirechannel is defined by both the arterial segment 624 and venous segment622. So configured, a guidewire extending distally from a proximalportion of the first lumen and passing through the portion of the firstlumen defined by the venous segment 622, then through the guidewirechannel 632B to exit its corresponding opening on the distal end of thearterial segment 624 enables the venous and arterial segments to bemaintained in a joined configuration during catheter insertion.

The venous segment 622 includes a venous lateral opening 642 proximatethe nose portion 630, while the arterial segment 624 includes anarterial lateral opening 644 proximate the distal end thereof. Thelateral openings 642, 644 define a triangular shape and are in fluidcommunication with the first and second lumens, respectively, of thecatheter body 11. The nose portion 630 of the present embodiment has arounded shape, in contrast to the tapered nose portion 30 of FIG. 1,though it is appreciated that various nose portion shape configurationsare possible. Also, it is appreciated that the lateral openings can eachdefine one of a variety of configurations.

FIGS. 19A-19D depict a distal tip region 720 of a split-tip catheterassembly including a venous segment 722 and an arterial segment 724 thattogether define a nose portion 730. The venous segment 722 includes avenous distal opening 732A in fluid communication with a first lumen ofthe catheter body 11. The arterial segment 724 includes a distal openingas part of a guidewire channel 732B. As best seen in FIG. 19D, theguidewire channel 732B is in fluid communication with a second lumen ofthe catheter body 11, but is angled so as to also communicate with thefirst lumen defined by the venous segment 722. Thus, the guidewirechannel is defined by both the arterial segment 724 and venous segment722. So configured, a guidewire extending distally from a proximalportion of the first lumen and passing through the portion of the firstlumen defined by the venous segment 722, then through the guidewirechannel 732B to exit its corresponding opening on the distal end of thearterial segment 724 enables the venous and arterial segments to bemaintained in a joined configuration during catheter insertion.

The venous segment 722 includes a venous lateral opening 742 proximatethe nose portion 730, while the arterial segment 724 includes anarterial lateral opening 744 proximate the distal end thereof. Thelateral openings 742, 744 define a triangular shape and are in fluidcommunication with the first and second lumens, respectively, of thecatheter body 11. The nose portion 730 of the present embodiment has arounded shape, in contrast to the tapered nose portion 30 of FIG. 1,though it is appreciated that various nose portion shape configurationsare possible. Also, it is appreciated that the lateral openings can eachdefine one of a variety of configurations.

FIGS. 20A-20C depict a distal tip region 820 of a split-tip catheterassembly including a venous segment 822 and an arterial segment 824. Thevenous segment 822 includes a venous opening 848 in fluid communicationwith a first lumen of the catheter body 11. Similarly, the arterialsegment 824 includes an arterial opening 846 in fluid communication witha second lumen of the catheter body 11. The openings 846, 848 aredisposed at i.e., coincident with, distal ends of the respective venousand arterial segments 822, 824 and extend proximally therefrom in anangled direction so as to define a triangular opening. Moreover, thevenous opening 848 is oppositely disposed as a mirror image of thearterial opening 846 such that each can direct fluid away from the otheropening during fluid infusion into the vessel, thus decreasingrecirculation and increasing catheter efficiency. Moreover, the openings846, 848 are sized so as to assist in fanning out fluid exitingtherefrom. In addition, the split tip configuration of the distal tipregion 820 further separates the venous opening 848 from the arterialopening 846, further improving catheter efficiency. Of course, it isappreciated that the venous and arterial openings of the presentembodiment can each define one of a variety of configurations.

Guidewire holes 850 are included on an inward-pointing distal surface ofboth the venous segment 822 and arterial segment 824 so as to enable theguidewire 46 to be passed therethrough to maintain the two segments in ajoined, or contact, configuration during catheter insertion procedures.

FIGS. 21A-21C depict a distal tip region 920 of a split-tip catheterassembly comprising many elements similar to the embodiment discussedabove in connection with FIGS. 20A-20C, including a venous segment 922defining a venous opening 948, an arterial segment 924 defining anarterial opening 946, and guidewire holes 950. In contrast to theprevious embodiment, however, the arterial segment 924 is shortened soas to be staggered proximally with respect to the venous segment 922 toprovide further opening separation.

FIGS. 22A-22B depict a distal tip region 1020 of a split-tip catheterassembly according to one embodiment, including a venous segment 1022and an arterial segment 1024 that selectively seats, or nests, in arecess defined by the venous segment. A nose portion 1030 of the venoussegment 1022 includes a venous distal opening 1032A in fluidcommunication with a first lumen 12 of the catheter body 11 and aguidewire channel 1032B. The arterial segment 1024 includes an arterialdistal opening 1034 in fluid communication with a second lumen 14 of thecatheter body 11. As shown, a spacing S exists between a proximal end ofthe nose portion 1030A and a distal end of the arterial segment 1024whereon is defined the arterial distal opening 1034. Thus, though seatedin the recess of the venous segment 1022, the arterial segment 1024 doesnot occupy the entirety of the recess. A guidewire can span the spacingS between the nose portion 1030 and the arterial distal opening 1034 tomaintain the arterial segment 1024 seated in the recess of the venoussegment 1022.

The venous segment 1022 includes a plurality of venous lateral openings1042 proximal to the nose portion 1030, while the arterial segment 1024also includes a plurality of arterial lateral openings 1044 proximal tothe distal end thereof. The lateral openings 1042 and 1044 are in fluidcommunication with the first and second lumens 12, 14, respectively, ofthe catheter body 11 and are spaced apart to preclude or lessen vesselwall suck-up.

FIGS. 23A-23C depict a distal tip region 1120 of a split-tip catheterassembly including a venous segment 1122 and an arterial segment 1124that together define a nose portion 1130. The venous segment 1122includes a venous distal opening 1132A in fluid communication with afirst lumen of the catheter body 11. The arterial segment 1124 includesan arterial distal opening 1134 in fluid communication with a secondlumen of the catheter body 11. The distal ends of the venous andarterial segments 1122, 1124 are angled so as to define the nose portion1130 with a tapered shape.

The venous segment 1122 includes a plurality of venous outer lateralopenings 1142A and venous inner lateral openings 1142B proximal to thenose portion 1130. Likewise, the arterial segment 1124 includes aplurality of arterial outer lateral openings 1144A and arterial innerlateral openings 1144B proximal to the nose portion 1130. The lateralopenings 1142A, B and 1144 A, B are in fluid communication with thefirst and second lumens, respectively, of the catheter body 11 and arespaced apart to preclude or lessen vessel wall suck-up.

The distal ends of the venous segment 1122 and arterial segment 1124 areun-staggered with respect to one another so as to enable both lateralopening sets 1142A, B and 1144 A, B to be placed in a single desiredlocation within the patient's vasculature, such as in the SVC forinstance. The venous segment 1122 and arterial segment 1124 can bemaintained in a contact configuration via the use of a guidewire thatextends through the inner lateral openings 1142B, 1144B, for instance.

FIGS. 24A-30 describe distal tip regions of the catheter body 11configured according to other example embodiments. It should beappreciated that the distal tip regions to be described below can beincluded with hemodialysis catheters or with other catheters, such ascentral venous catheters, for example.

Reference is now made to FIGS. 24A-24F, which depict various detailsregarding a distal tip region, generally designated at 1220, accordingto one embodiment. The distal tip region 1220 generally includes thedistal portion of the catheter assembly 10, including terminal distalportions of the first lumen 12 and second lumen 14. In the discussionbelow, it is understood that in one embodiment the first lumen 12 isconsidered a venous lumen for returning treated blood to the vessel andthe second lumen 14 is considered the arterial lumen for uptake of bloodfrom the vessel. As already mentioned, however, these duties of thefirst and second lumens may be reversed. Thus, these designations aremerely used herein for purposes of convenience.

The distal portion 1220 includes a nose portion 1230 at the distal endthereof. In the present embodiment, the nose portion 1230 generallydefines a tapered, generally conical shape, though it is appreciatedthat the nose portion may define other circumferentially convergentshapes, including hemispherical or bullet-shapes, frustoconical, andother smooth and/or contoured shapes that converge toward the distalend. The nose portion 1230 is therefore atraumatic, reducing insertionforces during placement and minimizing abrasion between the nose portionsurface and the walls of the vessel in which the distal region of thecatheter is disposed, thus reducing vascular injury. In contrast toprevious embodiments, the distal portion 1220 does not include separatesplit tip portions, but is a unitary, or solid-body, structure, definingdistal portions of the first and second lumens 12, 14 (FIGS. 25A, 25B).

The catheter body 11 defines a venous distal opening 1232A on thetapered surface of the nose portion 1230 so as to be in fluidcommunication with the distal portion of the first lumen 12. Thecatheter body 11 further defines an arterial distal opening 1232B at thedistal end of the nose portion 1230 so as to be in fluid communicationwith the second lumen 14. The openings of both the venous and arterialdistal openings 1232A, 1232B face in the distal direction for fluid flowpurposes as will be described. The second lumen 14 and correspondingarterial distal opening 1232B in the current embodiment can receive aguidewire therethrough for enabling over-the-wire placement of thecatheter 10. The first lumen 12 and corresponding venous distal opening1232A can also be used for receiving a guidewire therethrough, ifdesired. Of course, the venous and arterial distal opening, as well asthe other catheter openings to be described below, can vary in size andplacement from what is explicitly described herein.

FIGS. 24A-24F further depict the distal portion 1220 as including alongits length a venous lateral opening 1242 and an arterial lateral opening1244 defined by the catheter body 11 proximate the nose portion 1230.The lateral openings 1242 and 1244 can take various shapes andconfigurations, but in the present embodiment the lateral openings aredefined by compound-angle cross-drilled cuts through the outer surfaceof the catheter body 11 to establish fluid communication with therespective first or second lumens 12, 14. In one embodiment, such cutsare referred to as “skive” cuts.

In one embodiment and as best seen in FIG. 24F, the longitudinal axis ofeach cross cut of the lateral openings 1242, 1244 defines an angle θ₁ ofabout 35 degrees with a longitudinal axis 1246 of the catheter body 11in the perspective shown in FIG. 24F, though this angle can vary in oneembodiment from about 20 to about 90 degrees. In another embodiment, forexample the angle θ₁ can be defined at 30 degrees. The longitudinal axisof each cross cut of the lateral openings 1242, 1244 further defines anangle θ₂ in one embodiment of about 15 degrees with the longitudinalaxis 1246 in the perspective shown in FIG. 25A. In the perspective shownin FIG. 25A, the angle θ₂ can also be defined with respect to a planecoincident with the longitudinal axis 1246 that bisects the first lumen12 and second lumen 14, i.e., coplanar with the septum separating thefirst and second lumens, though this angle can vary in one embodimentfrom about 0 to about 45 degrees. In another embodiment, for example,angle θ₂ is defined at 25 degrees.

This angular character imparts both a lateral, or radial, directionalcomponent, as well as a longitudinal directional component to fluid flowout of either lateral opening 1242, 1244, as represented by the flowarrows in FIG. 24F. So configured, the lateral openings 1242, 1244 makeit such that fluid exiting the catheter from the venous lateral opening1242 is imparted a flow direction that is substantially opposite in aradial direction and substantially similar in a longitudinal directionto fluid that would exit the catheter from the arterial lateral opening1244. This aspect assists in reducing blood recirculation via thecatheter 10.

Note that, in one embodiment, the angle defined by each lateral openingcan be different. In another embodiment, non-compound-angle cross cutsmay be used to define the lateral openings. It should be appreciatedthat the particular angular configuration of the lateral openings canvary from what is described herein while still residing within the scopeof embodiments of the present invention.

In the present embodiment, the cross cut that defines the lateralopenings 1242, 1244 is achieved via use of a cylindrical drill bit orcoring tool having a size sufficient to define the lateral openinghaving the compound angle described above. For instance, in oneembodiment a drill bit is used to diagonally cross cut the venous andarterial lateral openings 1242, 1244 through the catheter body. Notethat the catheter body size in one embodiment can vary from 7-16 Fr.,though other French sizes are also possible. Note here that, thoughidentically sized and shaped in the present embodiment, the first andsecond openings could include respectively differing dimensions ifdesired or needed for a particular application. Of course, other methodsfor defining the lateral openings, including molding, cutting, heatforming, etc., may also be used.

As a result of defining the cross cuts as just described, the elongatevenous and arterial openings 1242, 1244 are defined by perimeters shapedin the present embodiment as a figure-eight shape, or analemma, whenviewed in a two-dimensional perspective and an elongate saddle shapewhen viewed in a three-dimensional perspective. “Elongate” and“elongated” are understood herein as including a long or extended shape,or including more length than width. Again, this enables the lateralopenings 1242, 1244 to partially extend longitudinally andcircumferentially about the outer perimeter of the catheter body 11.This helps to prevent undesired suctioning of the distal tip region 1220to the vessel wall when one of the openings is removing blood from thevessel as the negative flow pressure of the opening is distributed abouta portion of the catheter body circumference. If vessel suck-up doesoccur, the lateral openings 1242, 1244 are shaped so as to nonethelessprovide acceptable fluid flow in and out of the catheter assembly 10.The relatively large size of the lateral openings 1242, 1244 alsoassists in the prevention of occlusion or sheath formation and providesa fanned-out or wide distribution of fluid flowing out therefrom.Recirculation efficiency rates are improved as a result.

In addition, the longitudinal axes of the lateral openings 1242, 1244are symmetrically opposed in direction from one another, as best shownin FIG. 24D, to produce a “criss-cross” relationship between the lateralopenings. This ensures that fluid entry and exit from the lateralopenings occurs on opposite sides of the catheter body 11, thus furtherreducing recirculation of already treated blood. Furthermore, thissymmetry ensures similar fluid flow characteristics to be realized evenwhen fluid flow through the catheter assembly 10 is reversed.

It is noted that in one embodiment the size of the lateral openings1242, 1244 is such that each can accommodate the entirety of fluid flowthrough their respective first or second lumens 12, 14. Thus, theinclusion of the lateral openings 1242, 1244 with their correspondingdistal openings 1232A, 1232B provides a redundant system such that anyclotting that occurs at one opening will not significantly impact fluidthroughput of the respective lumen. In addition, the lateral openingconfiguration described herein minimizes radical redirection of thefluid upon exiting the catheter body 11 via either of the lateralopenings 1242 and 1244, which in turn prevents fluid turbulence andpossible clotting or hemolysis.

FIGS. 24A-24F show that in the present embodiment the venous andarterial lateral openings 1242 and 1244 are substantially un-staggered,i.e., equally placed with respect to one another along the longitudinallength of the catheter body 11 such that each is substantially disposedan equal distance from the distal catheter end 11B. Such un-staggereddisposal of the lateral openings 1242 and 1244 enables both openings tobe placed proximate a desired anatomical location within the vasculatureand ensures that the recirculation rate of already treated blood throughthe catheter assembly 10 is held relatively constant regardless therespective directions of blood travel in/out of the lateral openings.This feature is useful should reversal of blood flow directions throughthe catheter be necessary. In one embodiment, the recirculation rate ineither direction is less than or equal to about five percent. In anotherembodiment, the position of the venous and lateral openings can bestaggered.

It should be appreciated that the labels “venous” and “arterial” as usedabove in describing the various components of the present catheter areemployed for sake of convenience in describing aspects of embodiments ofthe present invention. Indeed, though the second (arterial) lumen 14 isnormally employed in hemodialysis procedures for aspirating blood fromthe blood vessel in which the catheter is disposed and the first(venous) segment 12 for returning already treated blood to the vessel,this can be reversed such that blood is returned via the arterialsegment and aspirated by the venous segment. As such, the presentinvention should not be considered limited by the use of this and otherdescriptive terminology herein.

In one embodiment, the nose portion 1230 is defined via a radiofrequency(“RF”) tipping process, but other forming processes may also be employedto define the distal tip region in accordance with other embodiments andas appreciated by one skilled in the art.

Reference is now made to FIGS. 25A and 25B in describing flowcharacteristics with respect to the configuration of the distal tipregion 1220 of the present catheter assembly 10. FIGS. 25A and 25B showthe distal tip region 1220 as in position after the catheter assembly 10has properly positioned within a vessel of a patient. Arrow 1248 showsthe direction of blood flow past the distal tip region 1220 within thepatient's vessel.

In greater detail, FIG. 25A shows fluid flow through the distal tipregion 1220 in a “forward” direction, or first staggered flowconfiguration, wherein blood is aspirated by the second lumen 14, or“uptake” lumen, for removal from the body and treatment by ahemodialysis apparatus or for some other suitable purpose. Aspiratedblood enters the second lumen 14 via both the arterial distal endopening 1232B and the arterial lateral opening 1244. However, becausethe second lumen 14 is under negative pressure during aspiration, themajority of blood aspirated by the second lumen is removed via thearterial lateral opening 1244 due to its relatively more proximalposition with respect to the pressure differential in the proximatevessel region.

Simultaneously, blood is infused, or returned, to the vessel by thefirst lumen 12, or “return” lumen, after treatment by a hemodialysisapparatus or some other suitable purpose. Infused blood exits the firstlumen 12 from both the venous distal opening 1232A and the venouslateral opening 1242. However, because the second lumen 12 is underpositive pressure during infusion, the majority of blood returned to thebloodstream by the first lumen exits via the venous distal opening 1232Adue to its relatively more distal position with respect to the pressuredifferential in the proximate vessel region. Note that this arrangementproduces an effective stagger distance F in the “forward” directionbetween the primary aspiration site, i.e., the arterial lateral opening1244, and the primary infusion site, i.e., the venous distal opening1232A. This effective stagger distance, together with the lateralorientation of the lateral openings 1242, 1244 provides for lowrecirculation of already-treated blood within the vessel, recirculationbeing defined as already-treated blood that is returned to thebloodstream via the venous lumen being immediately aspirated by thearterial lumen to be re-treated. Such recirculation is undesirable as itresults in lower treatment efficiency and longer treatment time.

During hemodialysis procedures, it is sometimes necessary to reverse theblood flow through the catheter assembly 10. FIG. 25B shows fluid flowthrough the distal tip region 1220 during such a “reverse” flowsituation, or second staggered flow configuration. In contrast to theforward flow conditions of FIG. 25A, the second lumen 14 in FIG. 25B isemployed to infuse blood into the vessel, while the first lumen 12aspirates blood from the vessel. In this configuration, the majority ofinfused blood enters the vessel via the arterial distal opening 1232B,while the majority of aspirated blood is removed via the venous lateralopening 1242. This arrangement produces an effective stagger distance Rin the “reverse” direction between the primary aspiration site, i.e.,the venous lateral opening 1242, and the primary infusion site, i.e.,the arterial distal opening 34. Thus, it is seen that a desired staggerbetween the primary infusion and aspiration points is achievedregardless of the direction in which the catheter is operating. In oneembodiment, the effective stagger distance F in the forward direction isabout 0.04 inch, while the effective stagger distance R in the reversedirection is about 0.6 inch, though the lateral and distal openings canbe varied to produce other stagger distances. This can be compared toforward and reverse effective stagger distances of about 0.43 inch andabout 0.23 inch, respectively, for the split-tip configuration shown inFIGS. 3A-3D. In one embodiment, both the forward and reverse effectivestagger distances for the catheters described herein can be in a rangeof from about 0.1 inch to about 1 inch, though other distances can alsobe achieved.

In one embodiment, the catheter body 11 can define one or more arterialside holes 1249 that are in communication with the second lumen 14 toassist in providing desired fluid flow via the second lumen. In thepresent embodiment, the side holes 1249 each define a diameter of about0.030 inch, compared with the arterial distal opening 1232B, whichdefines an opening of about 0.040 inch. Though shown here as round, theside holes can include other shapes and sizes as well. In otherembodiments, the first lumen can include additional side holes as well.

As shown in FIGS. 25A-25C, the first and second lumens 12, 14, eachinclude a transition region 1245 in which region the cross sectionalshape of each lumen changes from a “D”-shape to an oval shape in aconfiguration similar to that described in connection with FIGS. 5C-5G.FIG. 25C depicts further narrowing of the lumen 14 in one embodiment inthe nose portion 1230 proximate the arterial distal opening 1232B. It isappreciated that other lumen size configurations can also be used inother embodiments. Indeed, in other embodiments narrowing of the one orboth lumens can occur proximal to the distal tip region, or only at thedistal end thereof. In still other embodiments, no narrowing of thelumens through the distal tip region occurs. FIG. 26A shows an exteriordistal end view of the distal tip portion 1220 of the catheter assembly10, while FIG. 26B shows a distal facing internal view thereof.

FIG. 27 depicts the catheter assembly 10 after placement in thevasculature of a patient 1250, wherein a tunneled region 1252intermediate the proximal and distal ends of the catheter body 11 isdisposed underneath the skin of the patient. As shown, the proximalportion of the catheter assembly 10, including the hub 15 and extensionlegs 16 and 18, is exposed proximal the tunneled region 1252.Correspondingly, a distal portion of the catheter assembly 10 is showndistal of the tunneled region 1252 and inserted through an incision site1254 into the patient's vasculature such that the distal tip region 1220is positioned in a desired location, such as in a lower region of thesuperior vena cava (“SVC”). The cuff 19 (FIG. 1) is included in thetunneled region 1252 of the catheter assembly 10 such that tissuein-growth into the cuff may be achieved to subcutaneously anchor thecatheter to the patient's body and prevent unintended movement of thecatheter. The process by which the tunneling configuration shown in FIG.27 is achieved is referred to as antegrade tunneling. Note, however,that the catheter 10 can be placed by other insertion and tunnelingmethods as well.

Reference is now made to FIGS. 28A-28D, which depict various aspects ofthe catheter body 11, according to another example embodiment. Notethat, as the present catheter body shares various details with thecatheter body described in previous embodiments, only selecteddifferences are discussed here. The catheter body 11 of FIGS. 28A-28Dcomprises the distal tip region 1220, which in turn includes the venouslateral opening 1242 and the arterial lateral opening 1244, each definedby the catheter body. A venous distal opening 1332A and an arterialdistal opening 1332B are also included in the distal tip region 1220, asdefined by the catheter body 11. In contrast to earlier embodiments, thevenous distal opening 1332A is defined as to be relatively larger thanthe venous distal opening 1232A of FIG. 26A, while the arterial distalopening 1332B is also defined to be larger relative to the arterialdistal opening 1232B shown in FIG. 26A. The relatively larger sizes ofthe distal openings provide for enhanced fluid flow therethrough. Asbest seen in FIG. 28B, the distal profile of the distal tip region 1220is relatively less tapered when compared to the profile of FIG. 25A,though it is appreciated that the profile and relative sizes of thelateral and distal openings of the distal tip region can be modified invarious ways, as appreciated by one skilled in the art.

FIGS. 29A and 29B depict yet another example embodiment of the catheterbody 11, wherein the distal tip portion 1220 comprises a plurality ofdistal end openings defined by the catheter body, including a venousdistal opening 1432A and symmetrically opposed arterial distal opening1432B. The openings 1432A and 1432B are each defined as circular segmentopenings so as to promote lateral and distal distribution of fluidflowing out therefrom. Their symmetrical opposition as best seen in FIG.29A reduces the likelihood of blood recirculation. The nose of thecatheter body is tapered in the illustrated embodiment, though other tipshapes are also possible.

A guidewire hole 1432C is also defined at the distal end of the catheterbody 11, and is in communication with one of the catheter body lumens,such as the first lumen 12. This enables a guidewire to pass through thefirst lumen 12 and out the guidewire hole 1432C to enable the catheterto be placed by over-the-guidewire techniques.

FIG. 30 depicts the catheter body 11 one possible embodiment, whereinthe lateral openings 1242, 1244 are longitudinally staggered withrespect to one another so as to provide substantially equal effectivestagger distances in both the forward (F′) and reverse (R′) directions,during hemodialysis procedures as described above in connection withFIGS. 25A, 25B. As such, it should be appreciated that relativepositioning of the lateral and distal openings may vary from what isdescribed herein while still residing within the scope of the presentclaims, and that such variation in the lateral and distal openings canbe applied to the split-tip as well as the unitary (solid-body) catheterconfigurations described herein.

It is appreciated that other lumen size configurations can also be usedin other embodiments. Indeed, in other embodiments narrowing of one orboth lumens can occur proximal to the distal tip region, or only at thedistal end thereof. In still other embodiments, no narrowing of thelumens through the distal tip region occurs.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrative,not restrictive. The scope of the invention is, therefore, indicated bythe appended claims rather than by the foregoing description. Allchanges that come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed is:
 1. A catheter for vascular insertion, comprising: acatheter body including an outer wall enclosing a first lumen and asecond lumen, the first lumen separated from the second lumen by aseptum, the first lumen and the second lumen respectively terminating ata distal end of the catheter body in a first opening and a secondopening; a first lateral opening in fluid communication with the firstlumen at the distal end of the catheter body, the first lateral openingdefined by a skive cut through the outer wall of the catheter bodyproximal to the first opening, the skive cut defined by: a first cut atan angle relative to a longitudinal axis of the catheter body in a rangefrom about 20 degrees to about 90 degrees; and a second cut at an anglerelative to a plane through the septum of about 45 degrees or less; asecond lateral opening in fluid communication with the second lumen atthe distal end of the catheter body proximal to the second opening. 2.The catheter according to claim 1, wherein the first cut is about 30degrees, and wherein the second cut is about 25 degrees.
 3. The catheteraccording to claim 1, wherein the first cut is about 35 degrees, andwherein the second cut is about 25 degrees.
 4. The catheter according toclaim 1, wherein the first cut is about 30 degrees, and wherein thesecond cut is about 15 degrees.
 5. The catheter according to claim 1,wherein the first cut is about 35 degrees, and wherein the second cut isabout 15 degrees.
 6. The catheter according to claim 1, wherein thesecond lateral opening is defined by a skive cut through the outer wallof the catheter body, the skive cut defined by: a third cut at an anglerelative to a longitudinal axis of the catheter body in a range fromabout 20 degrees to about 90 degrees; and a fourth cut at an anglerelative to a plane through the septum of about 45 degrees or less. 7.The catheter according to claim 6, wherein the second lateral opening ispositioned at about a same longitudinal location at the distal end ofthe catheter body as the first lateral opening.
 8. The catheteraccording to claim 7, wherein the first lateral opening and the secondlateral opening are each sized to accommodate an entirety of fluid flowthrough the respective first lumen and second lumen.
 9. The catheteraccording to claim 7, wherein the first lateral opening is positionedwith respect to the second lateral opening such that fluid exiting thecatheter body through the first lateral opening is imparted a flowdirection that is substantially opposite in a radial direction andsubstantially similar in a longitudinal direction to fluid exiting thecatheter body through the second lateral opening.
 10. The catheteraccording to claim 1, wherein the second lateral opening islongitudinally staggered with respect to the first lateral opening. 11.The catheter according to claim 10, further including a side hole influid communication with the second lumen positioned distal of thesecond lateral opening.
 12. The catheter according to claim 1, wherein across-sectional shape of one of the first lumen and the second lumentransitions at a transition region from a “D” shape to an oval shape.13. The catheter according to claim 12, wherein the transition region isproximal to the first lateral opening and the second lateral opening.14. The catheter according to claim 1, further comprising an atraumaticnose portion at the distal end of the catheter body, the atraumatic noseportion defining the first opening and the second opening.